PROBLEM TO BE SOLVED: To provide an automatic water supply device which can be put into action in such a wide range that a minimum effective water top for putting the automatic water supply device into action is roughly around 20 cmAq. to around 350 cmAq.SOLUTION: The automatic water supply device is provided with: an aqueduct 102 one opening of which is communicated with a water path 101 through which irrigation water is supplied a valve main body 103 mounted on another opening of the aqueduct 102 a valve body 108 moving up and down pivotally around an optional supporting point 112a, closely kept into contact with and separated from the valve seat part 104 of the valve main body 103 at least a single arm 110 mounted so as to face the supporting point 112a with a central focus on the valve body 108 at least a single tank 111 having an air breeder 115 mounted on the arm 110 and watershed pipes 117a, 117b, 117c which are communicated with the valve main body 103 and branches in mid-course, and one end parts of which are communicated with a water-level sensor 119 and the other end parts of which are communicated with the tank 111 respectively. The center of gravity of the tank 111 when filled with water is set at a side of the valve body 108 apart from the supporting point 112a.COPYRIGHT: (C)2008,JPO&INPIT【課題】自動給水装置を作動させる最低有効水頭が、概ね20cmAq.程度から、350cmAq.程度の有効水頭までの広範囲にわたり作動させることのできる自動給水装置を提供する。【解決手段】一方の開口が用水が供給される水路101に連通された導水管102と、導水管102の他方の開口に設けられた弁本体103と、任意の支点112aを枢軸に上下動し、弁本体103の弁座部104に圧接離間する弁体108と、弁体108を中心にして支点112aと対向して設けられた少なくともひとつのアーム110と、アーム110に設けられたエアー抜き115を有する少なくともひとつのタンク111と、弁本体103に連通すると共に、途中で分岐されその一端部が水位センサ119に連通され、他端部がタンク111に連通される分水管117a、117b及び117cとを有し、タンク111の満水時の重心を支点112aよりも弁体108側に設ける。【選択図】図1
